How to make a powerful laser with your own hands, video. How to make a laser at home: technology DIY laser cutting of metal

When in household there is a need to cut a metal sheet, then you can’t do without a laser cutter, assembled with your own hands.

Second life for simple things

The home master is always will find application even those things that have fallen into disrepair. So, an old laser pointer can find a second life and turn into a laser cutter. In order to bring this idea to life, you will need:

Laser pointer.
Flashlight.
Batteries (it is better to take rechargeable ones).
CD/DVD-RW recorder with a drive with a working laser.
Soldering iron.
Screwdrivers included.

Work begins by removing the laser cutter from the drive. This is painstaking work that requires maximum attention. When removing the top fastener, you may come across a carriage with a built-in laser. It can move in two directions. The carriage must be removed with extreme care and all detachable devices and screws must be removed carefully. Next, you need to remove the red diode that performs the burning. This work can be done using a soldering iron. It should be noted that this important detail requires increased attention. It is not recommended to shake or drop it.

To increase the power of the laser cutter in the prepared pointer, it is necessary to replace the “native” diode with the one removed from the recorder.

The pointer should be disassembled sequentially and carefully. It unwinds and splits into pieces. The part that requires replacement is located at the top. If it is difficult to remove it, then you can help yourself with a knife, slightly shaking the pointer. A new one is installed in place of the original diode. You can secure it with glue.

The next stage of work is the construction of a new building. This is where an old flashlight comes in handy. Thanks to it, the new laser will be convenient to use and connect to power. The improved end part of the pointer is installed in the flashlight body. Then power is connected from the batteries to the diode. When connecting, it is very important to set the polarity correctly. Before assembling the flashlight, you need to remove the glass and the remaining parts of the pointer so that nothing interferes with the direct path of the laser beam.

Before using the assembled unit with your own hands, you need to once again check whether the laser is firmly fixed and level, and whether the polarity of the wires is connected correctly.

If everything is done correctly, the unit can be used. It will be difficult to work on metal, since the device has little power, but it is quite possible to burn through paper, polyethylene or something similar.

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Improved model

Can be made more powerful homemade laser ny cutter. To work you need to prepare:

CD/DVD-RW recorder (non-working model can be used).
Resistors 2-5 Ohm.
Batteries.
Capacitors 100 pF and 100 mF.
The wire.
Soldering iron.
Collimator.
LED flashlight in a steel housing.

A driver is assembled from these components, which will provide the cutter with the required power. It should be remembered that the current source is not directly connected to the diode. Otherwise it will become completely unusable. Power can only be connected through a ballast resistor.

The body with the lens acts as a collimator. It is she who will collect the rays into a single beam. This part can be purchased at a specialty store. The good part is that it has a socket for mounting a laser diode.

This laser is manufactured in the same way as the previous model. During work, it is necessary to use antistatic wristbands to remove static voltage from the laser diode. If it is not possible to purchase such bracelets, a thin wire can be used and wound around a diode. Then you can proceed to assembling the driver.

The possibility of making something useful out of unused or worn-out equipment attracts many home craftsmen. One of these useful devices is a laser cutter. Having such a device at their disposal (some even make it from ordinary laser pointer), can be performed decorative design products from various materials.

What materials and mechanisms will be required

To make a simple laser cutter with your own hands, you will need following materials And technical devices:

laser pointer;
a regular flashlight equipped with rechargeable batteries;
an old burner drive (CD/DVD-RW) equipped with a laser drive (it is not at all necessary that such a drive be in working condition);
soldering iron;
set of locksmith tools.

Thus, you can make a simple laser cutting device using materials that are easy to find in your home workshop or garage.

The process of making a simple laser cutter

The main working element homemade cutter The proposed design is a laser element of a computer disk drive. You should choose a writing drive model because the laser in such devices has a higher power, which allows you to burn tracks on the surface of the disk installed in them. The design of the read-type disk drive also contains a laser emitter, but its power, used only to illuminate the disk, is low.

The laser emitter, which is equipped with a recordable disk drive, is placed on a special carriage that can move in two directions. To remove the emitter from the carriage, it is necessary to free it from a large number of fasteners and detachable devices. They should be removed very carefully so as not to damage the laser element. Except ordinary tools, to remove the red laser diode (and this is what you need to equip a homemade laser cutter), you will need a soldering iron to carefully release the diode from the existing solder joints. When removing the emitter from its seat, you should be careful and careful not to expose it to strong mechanical stress, which could cause its failure.

The emitter, removed from the writing computer drive, must be installed instead of the LED that was originally equipped with the laser pointer. To perform this procedure, the laser pointer must be disassembled, dividing its body into two parts. In the top of them there is an LED, which should be removed and replaced with a laser emitter from a computer disk drive. When fixing such an emitter in the body of the pointer, you can use glue (it is only important to ensure that the eye of the emitter is located strictly in the center of the hole intended for the beam to exit).

The voltage generated by the power supplies in a laser pointer is not enough to ensure the efficiency of using a laser cutter, so it is not advisable to use them to equip such a device. For the simplest laser cutter, rechargeable batteries used in a regular electric flashlight are suitable. Thus, by combining the lower part of the flashlight, which houses its batteries, with the upper part of the laser pointer, where the emitter from the writing computer drive is already located, you can get a fully functional laser cutter. When performing such a combination, it is very important to maintain polarity batteries, which will supply electricity to the emitter.

Before assembling a homemade hand-held laser cutter of the proposed design, it is necessary to remove the glass installed in it from the tip of the pointer, which will impede the passage of the laser beam. In addition, you need to once again check the correct connection of the emitter with the batteries, as well as how accurately its eye is located in relation to the output hole of the pointer tip. Once all the structural elements are securely connected to each other, you can start using the cutter.

Of course, with such a low-power laser it will not be possible to cut a metal sheet, and it will not be suitable for woodworking, but it is suitable for solving simple problems associated with cutting cardboard or thin polymer sheets.

Using the algorithm described above, it is possible to produce a more powerful laser cutter, slightly improving the proposed design. In particular, such a device must be additionally equipped with such elements as:

capacitors whose capacitance is 100 pF and 100 mF;
resistors with parameters 2–5 Ohms;
collimator - a device that is used to collect light rays passing through it into a narrow beam;
LED flashlight with steel body.

Capacitors and resistors in the design of such a laser cutter are necessary in order to create a driver through which electrical power will flow from the batteries to the laser emitter. If you do not use a driver and apply current directly to the emitter, the latter may immediately fail. Despite the higher power, such laser machine It also won’t work for cutting plywood, thick plastic, and especially metal.

How to make a more powerful device

Home craftsmen are often interested in more powerful laser machines that they can make with their own hands. It is quite possible to make a laser for cutting plywood with your own hands and even a laser cutter for metal, but for this you need to acquire the appropriate components. In this case, it is better to immediately make your own laser machine, which will have decent functionality and work in automatic mode, controlled by an external computer.

Depending on whether you are interested in DIY or you need a device for working on wood and other materials, you should correctly select the main element of such equipment - a laser emitter, the power of which can be different. Naturally, do-it-yourself laser cutting of plywood is performed with a device of lower power, and a laser for cutting metal must be equipped with an emitter with a power of at least 60 W.

To make a full-fledged laser machine, including for cutting metal with your own hands, you will need the following Consumables and components:

a controller that will be responsible for communication between an external computer and the electronic components of the device itself, thereby ensuring control of its operation;
electronic board equipped with an information display;
laser (its power is selected depending on the materials for which the cutter being manufactured will be used);
stepper motors, which will be responsible for moving the device’s desktop in two directions (stepper motors from unused printers or DVD players can be used as such motors);
cooling device for the emitter;
DC-DC regulator, which will control the amount of voltage supplied to the electronic board of the emitter;
transistors and electronic boards for controlling stepper motors of the cutter;
Limit switches;
pulleys for installing timing belts and the belts themselves;
a housing, the size of which allows all the elements of the assembled structure to be placed in it;
ball bearings of various diameters;
bolts, nuts, screws, ties and clamps;
wooden boards, from which the working frame of the cutter will be made;
metal rods with a diameter of 10 mm, which will be used as guide elements;
a computer and a USB cable with which it will connect to the cutter controller;
set of locksmith tools.

If you plan to use a laser machine for do-it-yourself metal work, then its design must be reinforced to withstand the weight of the metal sheet being processed.

The presence of a computer and a controller in the design of such a device allows it to be used not only as a laser cutter, but also as an engraving machine. Using this equipment, the operation of which is controlled by a special computer program, it is possible to apply complex patterns and inscriptions to the surface of the workpiece with high precision and detail. The corresponding program can be found freely available on the Internet.

By design, the laser machine, which you can make yourself, is a shuttle-type device. Its moving and guiding elements are responsible for moving the working head along the X and Y axes. The Z axis is the depth to which the material being processed is cut. For moving the working head of a laser cutter of the presented design, as mentioned above, stepper motors are responsible, which are fixed on the stationary parts of the device frame and connected to the moving elements using toothed belts.

Movable carriage homemade cutting

Sliding support Head with laser and radiator Carriage assembly

Today we will talk about how to make a powerful green or blue laser yourself at home from scrap materials with your own hands. We will also consider drawings, diagrams and the design of homemade laser pointers with an igniting beam and a range of up to 20 km

The basis of the laser device is an optical quantum generator, which, using electrical, thermal, chemical or other energy, produces a laser beam.

Laser operation is based on the phenomenon of forced (induced) radiation. Laser radiation can be continuous, with constant power, or pulsed, reaching extremely high peak powers. The essence of the phenomenon is that an excited atom is capable of emitting a photon under the influence of another photon without its absorption, if the energy of the latter is equal to the difference in the energies of the levels of the atom before and after the radiation. In this case, the emitted photon is coherent with the photon that caused the radiation, that is, it is its an exact copy. This way the light is amplified. This phenomenon differs from spontaneous radiation, in which the emitted photons have random propagation directions, polarization and phase
The probability that a random photon will cause stimulated emission from an excited atom is exactly equal to the probability of absorption of this photon by an atom in an unexcited state. Therefore, to amplify light, it is necessary that there be more excited atoms in the medium than unexcited ones. In a state of equilibrium, this condition is not satisfied, so we use various systems pumping the laser active medium (optical, electrical, chemical, etc.). In some schemes, the laser working element is used as an optical amplifier for radiation from another source.

There is no external flow of photons in a quantum generator; an inverse population is created inside it using various pump sources. Depending on the sources there are various ways pumping:
optical - powerful flash lamp;
gas discharge in the working substance (active medium);
injection (transfer) of current carriers in a semiconductor in the zone
p-n transitions;
electronic excitation (irradiation of a pure semiconductor in a vacuum with a flow of electrons);
thermal (heating of gas followed by rapid cooling;
chemical (using the energy of chemical reactions) and some others.

The primary source of generation is the process of spontaneous emission, therefore, to ensure the continuity of generations of photons, the existence of a positive feedback is necessary, due to which the emitted photons cause subsequent acts of induced emission. To do this, the laser active medium is placed in an optical cavity. In the simplest case, it consists of two mirrors, one of which is translucent - through it the laser beam partially exits the resonator.

Reflecting from the mirrors, the radiation beam passes repeatedly through the resonator, causing induced transitions in it. The radiation can be either continuous or pulsed. At the same time, using various devices to quickly turn off and turn on the feedback and thereby reduce the period of the pulses, it is possible to create conditions for the generation of radiation very high power- these are the so-called giant impulses. This mode of laser operation is called Q-switched mode.
The laser beam is a coherent, monochrome, polarized, narrowly directed light flux. In a word, this is a beam of light emitted not only by synchronous sources, but also in a very narrow range, and directionally. A sort of extremely concentrated light flux.

The radiation generated by a laser is monochromatic, the probability of emission of a photon of a certain wavelength is greater than that of a closely located one, associated with the broadening of the spectral line, and the probability of induced transitions at this frequency also has a maximum. Therefore, gradually during the generation process, photons of a given wavelength will dominate over all other photons. In addition, due to the special arrangement of the mirrors, only those photons that propagate in a direction parallel to the optical axis of the resonator at a short distance from it are retained in the laser beam; the remaining photons quickly leave the resonator volume. Thus, the laser beam has a very small divergence angle. Finally, the laser beam has a strictly defined polarization. To do this, various polarizers are introduced into the resonator; for example, they can be flat glass plates installed at a Brewster angle to the direction of propagation of the laser beam.

The working wavelength of the laser, as well as other properties, depend on what working fluid is used in the laser. The working fluid is “pumped” with energy to produce an inversion effect of electronic populations, which causes stimulated emission of photons and an optical amplification effect. The simplest form The optical resonator consists of two parallel mirrors (there can also be four or more of them) located around the laser working fluid. The stimulated radiation of the working fluid is reflected back by the mirrors and is again amplified. Until the moment it comes out, the wave can be reflected many times.

So, let us briefly formulate the conditions necessary to create a source of coherent light:

you need a working substance with inverted population. Only then can light amplification be achieved through forced transitions;
the working substance should be placed between the mirrors that provide feedback;
the gain given by the working substance, which means the number of excited atoms or molecules in the working substance must be greater than a threshold value depending on the reflection coefficient of the output mirror.

Laser designs can be used following types working bodies:

Liquid. It is used as a working fluid, for example, in dye lasers. Includes: organic solvent(methanol, ethanol or ethylene glycol) in which chemical dyes (coumarin or rhodamine) are dissolved. The operating wavelength of liquid lasers is determined by the configuration of the dye molecules used.

Gases. In particular, carbon dioxide, argon, krypton or gas mixtures, as in helium-neon lasers. “Pumping” with the energy of these lasers is most often carried out using electrical discharges.
Solids (crystals and glasses). The solid material of such working fluids is activated (doped) by adding a small amount of chromium, neodymium, erbium or titanium ions. Commonly used crystals are: yttrium aluminum garnet, lithium yttrium fluoride, sapphire (aluminum oxide), and silicate glass. Solid-state lasers are usually "pumped" by a flash lamp or other laser.

Semiconductors. A material in which the transition of electrons between energy levels can be accompanied by radiation. Semiconductor lasers are very compact and “pumpable” electric shock, allowing them to be used in consumer devices such as CD players.

To turn an amplifier into an oscillator, it is necessary to organize feedback. In lasers, this is achieved by placing the active substance between reflecting surfaces (mirrors), forming a so-called “open resonator” due to the fact that part of the energy emitted by the active substance is reflected from the mirrors and again returns to the active substance

The Laser uses optical resonators of various types - with flat mirrors, spherical, combinations of flat and spherical, etc. In optical resonators that provide feedback in the Laser, only certain types of oscillations can be excited electromagnetic field, which are called natural oscillations or modes of the resonator.

Modes are characterized by frequency and shape, i.e., the spatial distribution of vibrations. In a resonator with flat mirrors, the types of oscillations corresponding to plane waves propagating along the axis of the resonator are predominantly excited. A system of two parallel mirrors resonates only at certain frequencies - and in the laser also plays the role that an oscillatory circuit plays in conventional low-frequency generators.

The use of an open resonator (and not a closed one - a closed metal cavity - characteristic of the microwave range) is fundamental, since in the optical range a resonator with dimensions L = ? (L is the characteristic size of the resonator, ? is the wavelength) simply cannot be manufactured, and at L >> ? a closed resonator loses its resonant properties because the number of possible types of oscillations becomes so large that they overlap.

The absence of side walls significantly reduces the number of possible types of oscillations (modes) due to the fact that waves propagating at an angle to the axis of the resonator quickly go beyond its limits, and allows maintaining the resonant properties of the resonator at L >> ?. However, the resonator in the laser not only provides feedback by returning radiation reflected from the mirrors to the active substance, but also determines the spectrum of the laser radiation, its energy characteristics, and the direction of the radiation.
In the simplest approximation of a plane wave, the condition for resonance in a resonator with flat mirrors is that an integer number of half-waves fits along the length of the resonator: L=q(?/2) (q is an integer), which leads to an expression for the frequency of the oscillation type with the index q: ?q=q(C/2L). As a result, the radiation spectrum of light, as a rule, is a set of narrow spectral lines, the intervals between which are identical and equal to c/2L. The number of lines (components) for a given length L depends on the properties of the active medium, i.e., on the spectrum of spontaneous emission at the quantum transition used and can reach several tens and hundreds. Under certain conditions, it turns out to be possible to isolate one spectral component, i.e., to implement a single-mode lasing mode. The spectral width of each component is determined by the energy losses in the resonator and, first of all, by the transmission and absorption of light by the mirrors.

The frequency profile of the gain in the working substance (it is determined by the width and shape of the line of the working substance) and the set of natural frequencies of the open resonator. For open resonators with a high quality factor used in lasers, the resonator passband ??p, which determines the width of the resonance curves of individual modes, and even the distance between neighboring modes ??h turn out to be less than the gain linewidth ??h, and even in gas lasers, where the line broadening is the smallest. Therefore, several types of resonator oscillations enter the amplification circuit.

Thus, the laser does not necessarily generate at one frequency; more often, on the contrary, generation occurs simultaneously at several types of oscillations, for which the amplification? more losses in the resonator. In order for the laser to operate at one frequency (in single-frequency mode), it is necessary, as a rule, to take special measures (for example, increase losses, as shown in Figure 3) or change the distance between the mirrors so that only one gets into the gain circuit. fashion. Since in optics, as noted above, ?h > ?p and the generation frequency in a laser is determined mainly by the resonator frequency, then in order to keep the generation frequency stable, it is necessary to stabilize the resonator. So, if the gain in the working substance covers the losses in the resonator for certain types of oscillations, generation occurs on them. The seed for its occurrence is, as in any generator, noise, which represents spontaneous emission in lasers.
In order for the active medium to emit coherent monochromatic light, it is necessary to introduce feedback, i.e., part of what is emitted by this medium luminous flux send back into the medium to produce stimulated emission. Positive feedback is carried out using optical resonators, which in the elementary version are two coaxially (parallel and along the same axis) mirrors, one of which is translucent, and the other is “deaf,” i.e., completely reflects the light flux. The working substance (active medium), in which an inverse population is created, is placed between the mirrors. Stimulated radiation passes through the active medium, is amplified, reflected from the mirror, passes through the medium again and is further amplified. Through a translucent mirror, part of the radiation is emitted into the external environment, and part is reflected back into the environment and amplified again. At certain conditions the flux of photons inside the working substance will begin to increase like an avalanche, and the generation of monochromatic coherent light will begin.

The principle of operation of an optical resonator, the predominant number of particles of the working substance, represented by open circles, are in the ground state, i.e., at the lower energy level. Just not a large number of particles, represented by dark circles, are in an electronically excited state. When the working substance is exposed to a pumping source, the majority of particles go into an excited state (the number of dark circles has increased), and an inverse population is created. Next (Fig. 2c) spontaneous emission of some particles occurring in an electronically excited state occurs. Radiation directed at an angle to the axis of the resonator will leave the working substance and the resonator. Radiation that is directed along the axis of the resonator will approach mirror surface.

For a translucent mirror, part of the radiation will pass through it into environment, and part of it will be reflected and again directed into the working substance, involving particles in an excited state in the process of stimulated emission.

At the “deaf” mirror, the entire radiation flux will be reflected and again pass through the working substance, inducing radiation from all remaining excited particles, which reflects the situation when all the excited particles gave up their stored energy, and at the output of the resonator, on the side of the translucent mirror, a powerful flux of induced radiation was formed.

The main structural elements of lasers include a working substance with certain energy levels of their constituent atoms and molecules, a pump source that creates population inversion in the working substance, and an optical cavity. There are a large number of different lasers, but they all have the same and simple schematic diagram device, which is shown in Fig. 3.

The exception is semiconductor lasers due to their specificity, since everything about them is special: the physics of the processes, pumping methods, and design. Semiconductors are crystalline formations. In an individual atom, the electron energy takes on strictly defined discrete values, and therefore the energy states of an electron in an atom are described in the language of levels. In a semiconductor crystal, energy levels form energy bands. In a pure semiconductor that does not contain any impurities, there are two bands: the so-called valence band and the conduction band located above it (on the energy scale).

Between them there is a gap of forbidden energy values, which is called the bandgap. At a semiconductor temperature equal to absolute zero, the valence band should be completely filled with electrons, and the conduction band should be empty. In real conditions, the temperature is always above absolute zero. But an increase in temperature leads to thermal excitation of electrons, some of them jump from the valence band to the conduction band.

As a result of this process, a certain (relatively small) number of electrons appears in the conduction band, and a corresponding number of electrons will be missing in the valence band until it is completely filled. An electron vacancy in the valence band is represented by a positively charged particle, which is called a hole. The quantum transition of an electron through the band gap from bottom to top is considered as a process of generating an electron-hole pair, with electrons concentrated at the lower edge of the conduction band, and holes at the upper edge of the valence band. Transitions through the forbidden zone are possible not only from bottom to top, but also from top to bottom. This process is called electron-hole recombination.

When a pure semiconductor is irradiated with light whose photon energy slightly exceeds the band gap, three types of interaction of light with matter can occur in the semiconductor crystal: absorption, spontaneous emission and stimulated emission of light. The first type of interaction is possible when a photon is absorbed by an electron located near the upper edge of the valence band. In this case, the energy power of the electron will become sufficient to overcome the band gap, and it will make a quantum transition to the conduction band. Spontaneous emission of light is possible when an electron spontaneously returns from the conduction band to the valence band with the emission of an energy quantum - a photon. External radiation can initiate the transition to the valence band of an electron located near the lower edge of the conduction band. The result of this third type of interaction of light with the semiconductor substance will be the birth of a secondary photon, identical in its parameters and direction of movement to the photon that initiated the transition.

To generate laser radiation, it is necessary to create an inverse population of “working levels” in the semiconductor—to create a sufficiently high concentration of electrons at the lower edge of the conduction band and a correspondingly high concentration of holes at the edge of the valence band. For these purposes, pure semiconductor lasers are usually pumped by an electron flow.

The resonator mirrors are polished edges of the semiconductor crystal. The disadvantage of such lasers is that many semiconductor materials generate laser radiation only at very low temperatures, and the bombardment of semiconductor crystals by a stream of electrons causes it to become very hot. This requires additional cooling devices, which complicates the design of the device and increases its dimensions.

The properties of semiconductors with impurities differ significantly from the properties of unimpurity, pure semiconductors. This is due to the fact that atoms of some impurities easily donate one of their electrons to the conduction band. These impurities are called donor impurities, and a semiconductor with such impurities is called an n-semiconductor. Atoms of other impurities, on the contrary, capture one electron from the valence band, and such impurities are acceptor, and a semiconductor with such impurities is a p-semiconductor. Energy level impurity atoms is located inside the band gap: for n-semiconductors - near the lower edge of the conduction band, for /-semiconductors - near the upper edge of the valence band.

If an electric voltage is created in this area so that there is a positive pole on the side of the p-semiconductor, and a negative pole on the side of the p-semiconductor, then under the influence electric field electrons from the n-semiconductor and holes from the n-semiconductor will move (inject) into the region of the p-n junction.

When electrons and holes recombine, photons will be emitted, and in the presence of an optical resonator, laser radiation can be generated.

The mirrors of the optical resonator are polished edges of the semiconductor crystal, oriented perpendicularly p-n plane— transition. Such lasers are miniature, since the size of the semiconductor active element can be about 1 mm.

Depending on the characteristic under consideration, all lasers are divided as follows).

First sign. It is customary to distinguish between laser amplifiers and generators. In amplifiers, weak laser radiation is supplied at the input, and it is correspondingly amplified at the output. There is no external radiation in the generators; it arises in the working substance due to its excitation using various pump sources. All medical laser devices are generators.

The second sign is the physical state of the working substance. In accordance with this, lasers are divided into solid-state (ruby, sapphire, etc.), gas (helium-neon, helium-cadmium, argon, carbon dioxide, etc.), liquid (liquid dielectric with impurity working atoms of rare earth metals) and semiconductor (arsenide -gallium, gallium arsenide phosphide, lead selenide, etc.).

The method of exciting the working substance is the third hallmark lasers. Depending on the excitation source, lasers are distinguished: optically pumped, pumped by a gas discharge, electronic excitation, injection of charge carriers, thermally pumped, chemically pumped, and some others.

The laser emission spectrum is the next classification feature. If the radiation is concentrated in a narrow range of wavelengths, then the laser is considered monochromatic and its technical data indicates a specific wavelength; if in a wide range, then the laser should be considered broadband and the wavelength range is indicated.

Based on the nature of the emitted energy, pulsed lasers and lasers with continuous radiation are distinguished. The concepts of a pulsed laser and a laser with frequency modulation of continuous radiation should not be confused, since in the second case we essentially receive intermittent radiation of various frequencies. Pulsed lasers have high power in a single pulse, reaching 10 W, while their average pulse power, determined by the corresponding formulas, is relatively small. For continuous frequency modulated lasers, the power in the so-called pulse is lower than the power of continuous radiation.

Based on the average radiation output power (the next classification feature), lasers are divided into:

· high-energy (the generated radiation power flux density on the surface of an object or biological object is over 10 W/cm2);

· medium-energy (generated radiation power flux density - from 0.4 to 10 W/cm2);

· low-energy (the generated radiation power flux density is less than 0.4 W/cm2).

· soft (generated energy irradiation - E or power flux density on the irradiated surface - up to 4 mW/cm2);

· average (E - from 4 to 30 mW/cm2);

· hard (E - more than 30 mW/cm2).

In accordance with " Sanitary standards and rules for the design and operation of lasers No. 5804-91”, according to the degree of danger of the generated radiation for operating personnel, lasers are divided into four classes.

First-class lasers include such technical devices whose output collimated (confined in a limited solid angle) radiation does not pose a danger when irradiating human eyes and skin.

Second class lasers are devices whose output radiation poses a danger when irradiating the eyes with direct and specularly reflected radiation.

Lasers of the third class are devices whose output radiation poses a danger when irradiating the eyes with direct and specularly reflected, as well as diffusely reflected radiation at a distance of 10 cm from a diffusely reflective surface, and (or) when irradiating the skin with direct and specularly reflected radiation.

Class 4 lasers are devices whose output radiation poses a hazard when the skin is irradiated with diffusely reflected radiation at a distance of 10 cm from a diffusely reflective surface.

Each of us held a laser pointer in our hands. Despite the decorative use, it contains a real laser, assembled on the basis of a semiconductor diode. The same elements are installed on laser levels and.

The next popular product assembled on a semiconductor is your computer's DVD burner drive. It contains a more powerful laser diode with thermal destructive power.

This allows you to burn a layer of the disc, depositing tracks with digital information on it.

How does a semiconductor laser work?

Devices of this type are inexpensive to produce and the design is quite widespread. The principle of laser (semiconductor) diodes is based on the use of classical p-n junction. This transition works the same as in conventional LEDs.

The difference is in the organization of radiation: LEDs emit “spontaneously”, while laser diodes emit “forced”.

The general principle of the formation of the so-called “population” of quantum radiation is fulfilled without mirrors. The edges of the crystal are mechanically chipped, providing a refractive effect at the ends, akin to a mirror surface.

To obtain different types of radiation, a “homojunction” can be used, when both semiconductors are the same, or a “heterojunction”, with different materials transition.

The laser diode itself is an accessible radio component. You can buy it in stores that sell radio components, or you can extract it from an old DVD-R (DVD-RW) drive.

Important! Even the simple laser used in light pointers can cause serious damage to the retina of the eye.

More powerful installations, with a burning beam, can deprive vision or cause burns skin. Therefore, when working with similar devices, use extreme caution.

With such a diode at your disposal, you can easily make a powerful laser with your own hands. In fact, the product may be completely free, or it will cost you a ridiculous amount of money.

DIY laser from a DVD drive

First, you need to get the drive itself. It can be removed from an old computer or purchased at a flea market for a nominal cost.

Making a powerful burning laser with your own hands is not a difficult task, however, in addition to the ability to use a soldering iron, you will need to be attentive and careful in your approach. It’s worth noting right away that deep knowledge from the field of electrical engineering is not needed here, and you can make a device even at home. The main thing when working is to take precautions, since exposure to a laser beam is harmful to the eyes and skin.

A laser is a dangerous toy that can cause harm to health if used carelessly. Do not point the laser at people or animals!

What will you need?

Any laser can be divided into several components:

light flux emitter;
optics;
power supply;
current supply stabilizer (driver).

To make a powerful homemade laser, you will need to consider all these components separately. The most practical and easiest to assemble is a laser based on a laser diode, which we will consider in this article.

Where can I get a diode for a laser?

The working element of any laser is a laser diode. You can buy it at almost any radio store, or get it from a non-working CD drive. The fact is that drive inoperability is rarely associated with failure of the laser diode. If you have a broken drive, you can extra costs get the required element. But you need to take into account that its type and properties depend on the modification of the drive.

The weakest laser, operating in the infrared range, is installed in CD-ROM drives. Its power is only enough to read CDs, and the beam is almost invisible and is not capable of burning objects. The CD-RW has a built-in more powerful laser diode, suitable for burning and designed for the same wavelength. It is considered the most dangerous, as it emits a beam in a zone of the spectrum invisible to the eye.

The DVD-ROM drive is equipped with two weak laser diodes, the energy of which is only enough to read CDs and DVDs. The DVD-RW burner contains a high-power red laser. Its beam is visible in any light and can easily ignite certain objects.

The BD-ROM contains a violet or blue laser, which is similar in parameters to the analogue from the DVD-ROM. From BD-RE recorders you can get the most powerful laser diode with a beautiful violet or blue beam capable of burning. However, it is quite difficult to find such a drive for disassembly, and working device it costs expensive.

The most suitable one is a laser diode taken from a DVD-RW drive. The highest quality laser diodes are installed in LG, Sony and Samsung drives.

The higher the DVD drive's writing speed, the more powerful the laser diode installed in it.

Drive disassembly

Having the drive in front of you, first remove the top cover by unscrewing 4 screws. Then remove the movable mechanism, which is located in the center and connected to printed circuit board flexible cable. The next goal is a laser diode, securely pressed into a radiator made of aluminum or duralumin alloy. It is recommended to provide protection against static electricity before dismantling it. To do this, the leads of the laser diode are soldered or wrapped with thin copper wire.

Next, there are two possible options. The first involves operating a finished laser in the form of a stationary installation together with a standard radiator. The second option is to assemble the device in the body of a portable flashlight or laser pointer. In this case, you will have to apply force to cut through or saw the radiator without damaging the radiating element.

Driver

Laser power supply must be handled responsibly. As with LEDs, it must be a stabilized current source. On the Internet there are many circuits powered by a battery or accumulator through a limiting resistor. The sufficiency of this solution is questionable, since the voltage on the battery or battery changes depending on the charge level. Accordingly, the current flowing through the laser emitting diode will deviate greatly from the nominal value. As a result, the device will not work efficiently at low currents, and at high currents it will lead to a rapid decrease in the intensity of its radiation.

The best option is to use a simple current stabilizer built on the basis. This microcircuit belongs to the category of universal integrated stabilizers with the ability to independently set the output current and voltage. The microcircuit operates in a wide range of input voltages: from 3 to 40 volts.

An analogue of LM317 is the domestic chip KR142EN12.

For the first laboratory experiment, the diagram below is suitable. The only resistor in the circuit is calculated using the formula: R=I/1.25, where I is the rated laser current (reference value).

Sometimes a polar capacitor of 2200 μFx16 V and a non-polar capacitor of 0.1 μF are installed at the output of the stabilizer in parallel with the diode. Their participation is justified in the case of supplying voltage to the input from a stationary power supply, which can miss an insignificant alternating component and impulse noise. One of these circuits, powered by a Krona battery or a small battery, is presented below.

The diagram shows the approximate value of resistor R1. To accurately calculate it, you must use the above formula.

Having assembled the electrical circuit, you can make a preliminary connection and, as proof of the circuit’s functionality, observe the bright red scattered light of the emitting diode. Having measured its actual current and body temperature, it is worth thinking about the need to install a radiator. If the laser will be used in a stationary installation at high currents long time, then it is necessary to provide passive cooling. Now there is very little left to achieve the goal: focus and get a narrow beam of high power.

Optics

In scientific terms, it's time to build a simple collimator, a device for producing beams of parallel light rays. The ideal option for this purpose would be a standard lens taken from the drive. With its help you can obtain a fairly thin laser beam with a diameter of about 1 mm. The amount of energy of such a beam is enough to burn through paper, fabric and cardboard in a matter of seconds, melt plastic and burn through wood. If you focus a thinner beam, this laser can cut plywood and plexiglass. But setting up and securely attaching the lens to the drive is quite difficult due to its small focal length.

It is much easier to build a collimator based on a laser pointer. In addition, its case can accommodate a driver and a small battery. The output will be a beam with a diameter of about 1.5 mm and a smaller burning effect. In foggy weather or heavy snowfall, you can observe incredible light effects by directing the light stream into the sky.

Through the online store you can purchase a ready-made collimator, specifically designed for mounting and tuning a laser. Its body will serve as a radiator. Knowing the dimensions of all the component parts of the device, you can buy a cheap LED flashlight and use its housing.

In conclusion, I would like to add a few phrases about the dangers of laser radiation. First, never point the laser beam into the eyes of people or animals. This leads to serious visual impairment. Secondly, wear green glasses when experimenting with the red laser. They block most of the red portion of the spectrum from passing through. The amount of light transmitted through the glasses depends on the wavelength of the radiation. Look from the side at the laser beam without protective equipment allowed only for a short time. Otherwise, eye pain may occur.